Image display apparatus and head-mounted display

ABSTRACT

An image display apparatus includes a plurality of light source sections, a light combining section that combines light fluxes, an optical scan section that swings around a first axis and a second axis to deflect a combined light from the light combining section for scanning, and a controller that controls an amplitude of the optical scan section around the first axis to be greater than that of the optical scan section around the second axis, wherein an optical axis of each of the light fluxes from the plurality of light source sections to the optical scan section and the first axis are present in a first plane, the optical scan section has a light reflection surface configured to be perpendicular to the first plane, and the light reflection surface is irradiated with the combined light and traveling in a direction inclined to a normal to the light reflection surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation patent application of U.S.application Ser. No. 13/908,484 filed Jun. 3, 2013, which claimspriority to Japanese Patent Application No. 2012-127450, filed Jun. 4,2012 both of which are expressly incorporated by reference herein intheir entireties.

BACKGROUND

1. Technical Field

The present invention relates to an image display apparatus and ahead-mounted display.

2. Related Art

For example, as an image display apparatus for displaying an image on ascreen, there is a known configuration including a light source and anoptical scanner that deflects light from the light source fortwo-dimensional scanning (see JP-A-2008-304726, for example).

The image display apparatus described in JP-A-2008-304726 includes aplurality of semiconductor lasers, a parallelizing lens thatparallelizes a laser light flux from each of the semiconductor lasers, apolarizing beam splitter that combines the plurality of laser lightfluxes, and a MEMS (optical scanner) that deflects the combined laserlight flux from the polarizing beam splitter for two-dimensionalscanning. A mirror provided in the MEMS is disposed to be perpendicularto a plane including the optical axis of the laser light flux from eachof the semiconductor lasers, and the mirror is irradiated with the laserlight flux traveling in a direction inclined to a normal to the mirror.In JP-A-2008-304726, the configuration described above is intended toreduce the size of the apparatus.

In the image display apparatus described in JP-A-2008-304726, the mirroris resonantly driven to swing in the in-plane direction in the plane ata large amplitude, whereas driven to swing in an out-of-plane direction(direction perpendicular to the plane) at an amplitude smaller than theamplitude in the in-plane direction. Since laser light LL is incident onthe mirror in a direction inclined in the in-plane direction to a normalto the mirror as described above, the large amplitude of the mirror inthe in-plane direction disadvantageously greatly distorts two ends of adrawable region S, which is a region of a screen, a wall surface, or anyother object that can be scanned with the laser light, as shown in FIG.8B, resulting in a decrease in area of a rectangular effective drawingregion (region actually irradiated with laser light for image display)S′ provided in the drawable region S. As a result, efficient laser lightscanning cannot be made, or excellent image display characteristicscannot be achieved.

That is, the image display apparatus described in

JP-A-2008-304726 is problematic in that reduction in size of theapparatus and provision of excellent image display characteristicscannot be achieved at the same time.

SUMMARY

An advantage of some aspects of the invention is to provide an imagedisplay apparatus capable of improving image display characteristics(enlarging effective drawing region, in particular) while reducing thesize of the apparatus and a head-mounted display including the imagedisplay apparatus.

An image display apparatus according to an aspect of the inventionincludes a plurality of light source sections each of which emits alight flux, a light combining section that combines the light fluxesemitted from the plurality of light source sections, an optical scansection that swings around a first axis and a second axis perpendicularto the first axis to deflect a combined light from the light combiningsection for two-dimensional scanning, and a controller that controls anamplitude of a swing motion of the optical scan section around the firstaxis to be greater than the amplitude of the swing motion of the opticalscan section around the second axis, an optical axis of each of thelight fluxes emitted from the plurality of light source sections anddirected through the light combining section toward the optical scansection and the first axis are present in a first plane, the opticalscan section has a light reflection surface configured to beperpendicular to the first plane when the optical scan section is notdriven, and the light reflection surface is irradiated with the combinedlight emitted from the light combining section and traveling in adirection inclined to a normal to the light reflection surface.

The image display apparatus described above has a small size andimproved image display characteristics (enlarged effective drawingregion, in particular).

In the image display apparatus according to the aspect of the invention,it is preferable that the optical scan section includes a movableportion having the light reflection surface, a frame that surrounds themovable portion, a support member that supports the frame, a first shaftthat connects the movable portion to the frame in such a way that themovable portion is swingable around the first axis relative to theframe, and a second shaft that connects the frame to the support memberin such a way that the frame is swingable around the second axisrelative to the support member.

The optical scan section described above has a simple configuration.Further, using the two-dimensional-scanning optical scanner allows thesize of the optical scan section to be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that a width of the frame in a direction perpendicularto the first plane is smaller than the width of the frame in an in-planedirection in the first plane.

The thickness of the image display apparatus can therefore be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the optical scan section further includes apermanent magnet provided on the frame and a coil that faces the frameand produces a magnetic field that acts on the permanent magnet.

In the configuration described above, the thickness of the optical scansection in the direction of a normal to the light reflection surfaceincreases, whereas the width of the optical scan section in the in-planedirection of the light reflection surface can be reduced. The thusshaped optical scan section is suitable for the image display apparatusaccording to the aspect of the invention.

In the image display apparatus according to the aspect of the invention,it is preferable that the light reflection surface resonantly swingsaround the first axis.

The light reflection surface can therefore be allowed to swing at alarge amplitude around the first axis in a simple, reliable manner.

It is preferable that the image display apparatus according to theaspect of the invention further includes a prism that is provided on anoptical path between the light combining section and the optical scansection, inclines an optical axis of the combined light from the lightcombining section, and changes a cross-sectional shape of the combinedlight.

Providing the prism increases the degree of freedom in arranging thecomponents in the apparatus, and shaping the cross-sectional shape ofthe light improves the image display characteristics.

In the image display apparatus according to the aspect of the invention,it is preferable that the light flux emitted from each of the lightsource sections is linearly polarized light that behaves as s-polarizedlight with respect to a light incident surface of the prism.

In this way, for example, loss of the light flux produced when the lightflux passes through the prism, which is an optical element, can bereduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the prism changes the cross-sectional shape of thecombined light from the light combining section by increasing a width ofthe combined light from the light combining section in an in-planedirection in the first plane.

An elliptical (or oval) cross-sectional shape of the light fluximmediately after it is emitted from each light source can thus bechanged to a substantially circular shape, whereby the image displaycharacteristics can be improved.

In the image display apparatus according to the aspect of the invention,it is preferable that a light exiting surface of the prism is a lightcollecting lens surface.

In this way, when an image is displayed on an object located in aposition in the vicinity of the focal point of the lens surface, betterimage display characteristics are provided.

It is preferable that the image display apparatus according to theaspect of the invention further includes a detector that detects anamount of light emitted from each of the light source sections andreflected off a light incident surface of the prism, and drive operationof the light source section is controlled based on the amount of lightdetected by the detector.

Light of a desired color and intensity can thus be produced, wherebyexcellent image display characteristics are provided.

In the image display apparatus according to the aspect of the invention,it is preferable that an angle of radiation of the light flux emittedfrom each of the plurality of light source sections and directed in adirection perpendicular to the first plane is set to be greater than theangle of radiation of the light flux emitted in an in-plane direction inthe first plane.

A laser light flux emitted from a semiconductor laser, which istypically used as a light source, has a substantially ellipticalintensity distribution. That is, the angle of radiation of the laserlight flux in the direction of the major axis of the ellipse differsfrom the angle of radiation of the laser light flux in the direction ofthe minor axis of the ellipse. For example, setting the direction of themajor axis, where the angle of radiation is larger, to be perpendicularto the first surface, allows the prism to be disposed in a horizontalattitude, whereby the size of the apparatus can be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the plurality of light source sections, the lightcombining section, and the optical scan section are arranged in anin-plane direction in the first plane.

The size (thickness) of the image display apparatus can thus be reduced.

An image display apparatus according to another aspect of the inventionincludes a plurality of light source sections each of which emits alight flux, a light combining section that combines the light fluxesemitted from the plurality of light source sections, and an optical scansection that swings around a first axis and a second axis perpendicularto the first axis to deflect a combined light from the light combiningsection for two-dimensional scanning, an optical axis of each of thelight fluxes emitted from the plurality of light source sections anddirected through the light combining section toward the optical scansection and the first axis are present in a first plane, the opticalscan section has a light reflection surface configured to beperpendicular to the first plane when the optical scan section is notdriven, the light reflection surface is irradiated with the combinedlight emitted from the light combining section and traveling in adirection inclined to a normal to the light reflection surface, and anamplitude of a swing motion of the optical scan section around the firstaxis is greater than the amplitude of the swing motion of the opticalscan section around the second axis.

The image display apparatus described above has a small size andimproved image display characteristics (enlarged effective drawingregion, in particular).

A head-mounted display according to still another aspect of theinvention includes a light reflector that reflects at least part oflight incident thereon, and an image display apparatus that irradiateslight to the light reflector, the image display apparatus including aplurality of light source sections each of which emits a light flux, alight combining section that combines the light fluxes emitted from theplurality of light source sections, an optical scan section that swingsaround a first axis and a second axis perpendicular to the first axis todeflect a combined light from the light combining section fortwo-dimensional scanning, and a controller that controls an amplitude ofa swing motion of the optical scan section around the first axis to begreater than the amplitude of the swing motion of the optical scansection around the second axis, an optical axis of each of the lightfluxes emitted from the plurality of light source sections and directedthrough the light combining section toward the optical scan section andthe first axis are present in a first plane, the optical scan sectionhas a light reflection surface configured to be perpendicular to thefirst plane when the optical scan section is not driven, and the lightreflection surface is irradiated with the combined light emitted fromthe light combining section and traveling in a direction inclined to anormal to the light reflection surface.

A reliable head-mounted display can thus be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view showing an image display apparatus according to apreferred embodiment of the invention.

FIG. 2 is a cross-sectional view of a laser light flux emitted from eachlaser light source shown in FIG. 1.

FIG. 3 is a side view of the image display apparatus shown in FIG. 1.

FIG. 4 is a plan view showing an optical scan section (optical scanner)provided in the image display apparatus shown in FIG. 1.

FIG. 5 is a cross-sectional view of the optical scanner shown in FIG. 4.

FIG. 6 is a block diagram of a voltage applying section provided in theoptical scanner shown in FIG. 4.

FIGS. 7A and 7B show examples of voltages generated by a first voltagegenerator and a second voltage generator shown in FIG. 6.

FIGS. 8A and 8B show a difference in drawable region caused by how theoptical scanner is disposed.

FIG. 9 is a perspective view showing a head-up display based on theimage display apparatus according to the embodiment of the invention.

FIG. 10 is a perspective view showing a head-mounted display accordingto an embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An image display apparatus and a head-mounted display according topreferred embodiments of the invention will be described below withreference to the accompanying drawings.

1. Image Display Apparatus

FIG. 1 is a plan view showing an image display apparatus according to apreferred embodiment of the invention. FIG. 2 is a cross-sectional viewof a laser light flux emitted from each laser light source shown inFIG. 1. FIG. 3 is a side view of the image display apparatus shown inFIG. 1. FIG. 4 is a plan view showing an optical scan section (opticalscanner) provided in the image display apparatus shown in FIG. 1. FIG. 5is a cross-sectional view of the optical scanner shown in FIG. 4. FIG. 6is a block diagram of a voltage applying section provided in the opticalscanner shown in FIG. 4. FIGS. 7A and 7B show examples of voltagesgenerated by a first voltage generator and a second voltage generatorshown in FIG. 6. FIGS. 8A and 8B show a difference in drawable regioncaused by how the optical scanner is disposed. In the followingdescription, the upper side in FIG. 5 is called “upper” and the lowerside in FIG. 5 is called “lower” for ease of description. Further, threeaxes perpendicular to each other are called an X axis, a Y axis, and a Zaxis, as shown in FIG. 1.

The image display apparatus 1 shown in FIG. 1 is an apparatus that scansan object 10, such as a screen and a wall surface, with light to displayan image.

The image display apparatus 1 includes a drawing light source unit 2,which emits drawing laser light LL, a prism 3, which inclines theoptical axis of the drawing laser light LL and deforms thecross-sectional shape of the drawing laser light LL, an optical scansection 4, which deflects the drawing laser light LL having passedthrough the prism 3 for scanning, a detector 5, which detects theintensity of the drawing laser light LL, and a controller 6, whichcontrols the operation of the drawing light source unit 2 and theoptical scan section 4.

The image display apparatus 1 has an enclosure 9, which has asmall-aspect shape having relatively large dimensions in the XY planeand a height in the Z-axis direction, and the enclosure 9 accommodatesthe drawing light source unit 2, the prism. 3, the optical scan section4, and the detector 5 arranged in the XY plane. The enclosure 9 in thisembodiment has a substantially rectangular exterior shape when viewedfrom above in the thickness direction of the enclosure 9. The enclosure9 further has a window 91 formed, for example, of a transparent member(made, for example, of glass or plastic), through which the drawinglaser light LL being deflected by the optical scan section 4 forscanning exits out of the enclosure 9. The controller 6 may beaccommodated in the enclosure 9 as in this embodiment or may be providedexternal to the enclosure 9.

The above components will be sequentially described below.

1-1. Drawing Light Source Unit

The drawing light source unit 2 includes laser light sources (lightsource sections) 21R, 21G, and 21B for the following colors: red; green;and blue and collimator lenses 22R, 22G, and 22B and dichroic mirrors23R, 23G, and 23B provided in correspondence with the laser lightsources 21R, 21G, and 21B, as shown in FIG. 1.

Each of the laser light sources 21R, 21G, and 21B has a light source anda drive circuit (not shown). The laser light source 21R emits a redlaser light flux RR. The laser light source 21G emits a green laserlight flux GG. The laser light source 21B emits a blue laser light fluxBB. The laser light fluxes RR, GG, and BB are emitted in accordance withdrive signals transmitted from the controller 6 and parallelized orsubstantially parallelized by the collimator lenses 22R, 22G, and 22B,respectively.

In this embodiment, the laser light sources 21R, 21B, and 21G arearranged in the -Y-axis direction in the order of the laser light source21R, the laser light source 21B, and the laser light source 21G anddisposed in the enclosure 9 in a left end portion thereof in FIG. 1. Thelaser light sources 21R, 21G, and 21B emit the laser light fluxes RR,GG, and BB, respectively, in the +X-axis direction. The thus arrangedlaser light sources 21R, 21G, and 21B occupy a relatively small space,allowing the size of the image display apparatus 1 (enclosure 9) to bereduced. It is noted that the arrangement of the laser light sources21R, 21G, and 21B is not limited to the arrangement described above.

Each of the laser light sources 21R, 21G, and 21B can, for example, bean edge-emitting semiconductor laser, a surface-emitting semiconductorlaser, or any other suitable semiconductor laser. Using a semiconductorlaser allows the size of each of the laser light sources 21R, 21G, and21B to be reduced.

When each of the laser light sources 21R, 21G, and 21B is formed of asemiconductor laser, the optical intensity distribution of each of thelaser light fluxes RR, GG, and BB emitted from the laser light sources21R, 21G, and 21B has in general a contour (what is called FFP: farfield pattern) having a substantially elliptical shape. It is assumed inthe following description that the “cross-sectional shape” of each ofthe laser light fluxes RR, GG, and BB has the same meaning as that ofthe “contour of the optical intensity distribution” of the correspondingone of the laser light fluxes RR, GG, and BB. That is, in this case,each of the laser light fluxes RR, GG, and BB emitted from the laserlight sources 21R, 21G, and 21B in other words has a substantiallyelliptical cross-sectional shape. The cross-sectional shape used hereinis the shape of a cross section perpendicular to the optical axis ofeach of the laser light fluxes RR, GG, and BB.

The laser light sources 21R, 21G, and 21B emit the laser light fluxesRR, GG, and BB, respectively, each of which has a substantiallyelliptical cross-sectional shape, as shown in FIG. 2. Each of the laserlight sources 21R, 21G, and 21B is so disposed in the enclosure 9 thatthe major axis of the ellipse substantially coincides with the Z axis(direction perpendicular to XY plane) and the minor axis of the ellipsesubstantially coincides with the Y axis (XY plane). In other words, eachof the laser light fluxes RR, GG, and BB emitted from the laser lightsources 21R, 21G, and 21B has an angle of radiation in the Z-axisdirection greater than the angle of radiation in the Y-axis direction(in-plane direction in XY plane). In this case, the three laser lightsources 21R, 21G, and 21B can be arranged in the Y-axis direction atnarrower intervals than in a case where the angles of radiation areconfigured in a reversed manner (in a case where the angle of radiationin the Z-axis direction is smaller than the angle of radiation in theY-axis direction), whereby the dimensions of the enclosure 9 in the XYplane can be reduced. The size of the image display apparatus 1 cantherefore be reduced.

Each of the laser light fluxes RR, GG, and BB emitted from the laserlight sources 21R, 21G, and 21B is linearly polarized light. Further,the laser light fluxes RR, GG, and BB are s-polarized light, which is alight component polarized in a direction perpendicular to thereflection/transmission surfaces (light incident surfaces) of thedichroic mirrors 23R, 23G, and 23B and the light incident surface of theprism 3. That is, each of the laser light fluxes RR, GG, and BB emittedfrom the laser light sources 21R, 21G, and 21B is polarized lightoscillating (polarized) in the Z-axis direction and has an ellipticalcross-sectional shape the major axis of which coincides with theoscillating direction. When each of the laser light fluxes RR, GG, andBB is s-polarized light, the amount of loss of the laser light fluxesRR, GG, and BB produced when they are incident on the dichroic mirrors23R, 23G, and 23B and the prism 3 can be reduced.

The dichroic mirror 23R is characterized in that it reflects the laserlight flux RR. The dichroic mirror 23B is characterized in that itreflects the laser light flux BB and transmits the laser light flux RR.The dichroic mirror 23G is characterized in that it transmits the laserlight flux GG and reflects the laser light fluxes RR and BB. Thedichroic mirrors 23R, 23G, and 23B cause the optical axes of the colorlaser light fluxes RR, GG, and BB to coincide or substantially coincide(be combined) with each other so that the single drawing laser light LLis emitted in the +X-axis direction. That is, the dichroic mirrors 23R,23G, and 23B form a light combining section 23, which combines the laserlight fluxes RR, GG, and BB with each other.

In this embodiment, the dichroic mirror 23R, the dichroic mirror 23B,and the dichroic mirror 23G are arranged in this order in the −Y-axisdirection in correspondence with the arrangement of the laser lightsources 21R, 21B, and 21G. The dichroic mirror 23R is so disposed thatit reflects the laser light flux RR emitted in the +X-axis directionfrom the laser light source 21R and causes the reflected light flux totravel in the −Y-axis direction. The dichroic mirror 23B is so disposedthat it not only reflects the laser light flux BB emitted in the +X-axisdirection from the laser light source 21B and causes the reflected lightflux to travel in the −Y-axis direction but also transmits the laserlight flux RR reflected off the dichroic mirror 23R in the −Y-axisdirection. Further, the dichroic mirror 23G is so disposed that it notonly transmits the laser light flux GG emitted in the +X-axis directionfrom the laser light source 21G but also reflects the laser light fluxesRR and BB reflected in the −Y-axis direction off the dichroic mirrors23R and 23B and causes the reflected light fluxes to travel in the+X-axis direction. The thus configured light combining section 23outputs the drawing laser light LL in the +X-axis direction.

The dichroic mirrors 23R, 23G, and 23B are preferably so disposed that alaser light flux of a shorter wavelength is incident on the prism 3 at agreater angle of incidence in consideration of dispersion resulting fromthe difference in refractive index among the wavelengths of the laserlight fluxes. That is, the dichroic mirrors 23R, 23G, and 23B aredisposed with their reflection surfaces slightly shifted from each otheraround the Z axis so that the following relationship is achieved: theangle of incidence θ_(B) of the blue laser light flux BB>the angle ofincidence θ_(G) of the green laser light flux GG>the angle of incidenceθ_(R) of the red laser light flux RR.

1-2. Prism

The prism 3 is an optical element having a first function of incliningthe optical axis of the drawing laser light LL, a second function ofdeforming the shape (cross-sectional shape) of the drawing laser lightLL, and a third function of controlling the angle of radiation of thedrawing laser light LL (collecting drawing laser light LL, for example).The prism 3 is a substantially colorless, transparent polyhedron made ofglass or quartz. The prism 3 is not limited to a specific one as long asit has the functions described above and can, for example, be atriangular prism having a substantially triangular columnar shape. Theangled portions of the triangular prism may, for example, be chamferedor otherwise rounded as long as the resultant shape does not affect thefunctions.

The first function will first be described. The prism 3 receives thedrawing laser light LL incident through a light incident surface 31 andoutputs the drawing laser light LL through a light exiting surface 32 ina direction inclined to the +X-axis direction toward the +Y-axisdirection (direction toward inner portion of enclosure 9). That is, theprism 3 inclines the optical axis of the drawing laser light LL aroundthe Z axis (in XY plane) . The thus configured prism 3 can direct thedrawing laser light LL toward an inner portion of the enclosure 9. Theenclosure 9 therefore has a space large enough to place members alongextensions of the optical axes of the light fluxes emitted from thelaser light sources 21R and 21B, and the internal space of the enclosure9 can be efficiently used by placing the optical scan section 4 in thespace. That is, inclining the optical axis of the drawing laser light LLtoward an inner portion of the enclosure 9 can reduce the volume of adead space (unused space where no member is disposed) in the enclosure9, whereby the size of the image display apparatus 1 can be reduced.

The second function described above will next be described. The prism 3changes the cross-sectional shape of the drawing laser light LL that isperpendicular to the optical axis thereof from the substantiallyelliptical shape to a substantially circular shape. Specifically, theprism 3 changes the cross-sectional shape of the drawing laser light LLto a substantially circular shape by increasing the width of thecross-sectional shape of the incident drawing laser light LL in thedirection in which the XY plane extends with the width thereof in theZ-axis direction substantially unchanged. In other words, the prism 3changes the cross-sectional shape of the drawing laser light LL in sucha way that the length of the minor axis of the ellipticalcross-sectional shape is increased to a point where the ratio betweenthe minor axis and the major axis (aspect ratio) is substantially one.When the cross-sectional shape of the drawing laser light LL becomes asubstantially circular shape as described above, the image displayapparatus 1 can provide excellent image display characteristics.Further, when the cross-sectional shape of the drawing laser light LLbefore it is incident on the prism 3 has a substantially ellipticalshape the major axis of which extends in the Z-axis direction asdescribed above, the prism 3 only needs to be angularly shifted in theXY plane, whereby the prism 3 can be so disposed that the length of theenclosure 9 in the thickness direction (Z-axis direction) correspondingto the space where the prism 3 occupies is minimized. As a result, thesize (thickness) of the image display apparatus 1 can be reduced.

The third function described above will next be described. The lightexiting surface 32 of the prism 3 is formed of a curved convex surface(lens surface) and hence functions as a collector lens that collects(focuses) the drawing laser light LL incident in the form ofparallelized light on the prism 3. Focusing the drawing laser light LLas described above can increase the sharpness of an image displayed onthe object 10 located in a position in the vicinity of the focal point(form an image having higher resolution). Further, the light exitingsurface 32 having a function of a collector lens eliminates thenecessity of separately providing a collector lens in addition to theprism 3, whereby the number of parts can be reduced and the size of theimage display apparatus 1 can be reduced. The light exiting surface 32of the prism 3 is not limited to a convex surface (collector lens) aslong as the light exiting surface 32 can control the angle of radiationof the light that exits through the light exiting surface 32 and can,for example, be a concave surface (lens that causes light to diverge).

The image display apparatus 1 does not necessarily use a prism but mayuse an optical element capable of providing the functions describedabove.

The drawing light source unit 2 and the prism 3 have been described indetail. In the image display apparatus 1, the optical axes of the laserlight fluxes RR, GG, and BB (drawing laser light LL) are present in thesame XY plane (first plane F), as shown in FIG. 3. That is, thefollowing actions are made in the plane F: The laser light sources 21R,21G, and 21B emit the laser light fluxes RR, GG, and BB; the lightcombining section 23 combines the laser light fluxes RR, GG, and BB andoutputs the resultant drawing laser light LL; and the prism 3 inclinesthe optical axis of the drawing laser light LL in the XY plane.

1-3. Optical Scan Section

The optical scan section 4 has a function of deflecting the drawinglaser light LL having passed through the prism 3 for two-dimensionalscanning. The optical scan section 4 is not limited to a specific oneand can be any device capable of deflecting the drawing laser light LLfor two-dimensional scanning. For example, an optical scanner 40 havingthe following configuration can be used.

The optical scanner 40 includes a movable portion 41, a pair of shafts421 and 422 (first shafts), a frame 43, two pairs of shafts 441, 442,443, and 444 (second shafts), a support member 45, a permanent magnet46, a coil 47, a magnet core 48, and a voltage applying section 49, asshown in FIGS. 4 and 5.

Among the components described above, the movable portion 41 and thepair of shafts 421 and 422 form a first oscillation system that swings(makes reciprocating motion) around the shafts 421 and 422 or a firstaxis J1. Further, the movable portion 41, the pair of shafts 421 and422, the frame 43, the two pairs of shafts 441, 442, 443, and 444, andthe permanent magnet 46 forma second oscillation system that swings(makes reciprocating motion) around a second axis J2. The permanentmagnet 46, the coil 47, and the voltage applying section 49 form adriver that drives the first and second oscillation systems describedabove.

The components of the optical scanner 40 will be sequentially describedbelow in detail.

The movable portion 41 includes a base 411 and a light reflection plate413 fixed to the base 411 via a spacer 412, as shown in FIGS. 4 and 5. Alight reflection portion 414, which reflects light, is provided on theupper surface (one surface) of the light reflection plate 413. Thesurface of the light reflection portion 414 forms a light reflectionsurface 414 a, which reflects the drawing laser light LL. The movableportion 41 swings around the first axis J1 and the second axis J2, asdescribed above. That is, it can be said that the base 411, the spacer412, the light reflection plate 413, and the light reflection surface414 a, which form the movable portion 41, also swing around the firstaxis J1 and the second axis J2.

The light reflection plate 413 is so disposed that it is set apart fromthe shafts 421 and 422 in the thickness direction of the lightreflection plate 413 but overlaps with the shafts 421 and 422 whenviewed in the thickness direction (hereinafter also referred to as “planview”).

The configuration described above allows the area of the plate surfaceof the light reflection plate 413 to be increased while allowing thedistance between the shaft 421 and the shaft 422 to be shortened.Further, since the distance between the shaft 421 and the shaft 422 canbe shortened, the size of the frame 43 can be reduced. Moreover, sincethe size of the frame 43 can be reduced, the distance between the shafts441, 442 and the shafts 443, 444 can be shortened. As a result, the sizeof the optical scanner 40 can be reduced with the area of the platesurface of the light reflection plate 413 increased.

The light reflection plate 413 is further so formed that it covers theentire shafts 421 and 422 in the plan view. In other words, the shafts421 and 422 are located inside the outer circumference of the lightreflection plate 413 in the plan view. The area of the plate surface ofthe light reflection plate 413 is thus increased, resulting in anincrease in the area of the light reflection portion 414. Theconfiguration further prevents unwanted light (light that has not beenincident on light reflection portion 414, for example) from beingreflected off the shafts 421 and 422 to form stray light.

The light reflection plate 413 is further so formed that it covers theentire frame 43 in the plan view. In other words, the frame 43 islocated inside the outer circumference of the light reflection plate 413in the plan view. The area of the plate surface of the light reflectionplate 413 is thus increased, resulting in an increase in the area of thelight reflection portion 414. The configuration further prevents theunwanted light from being reflected off the frame 43 to form straylight.

Further, the light reflection plate 413 is so formed that it covers theentire shafts 441, 442, 443, and 444 in the plan view. The area of theplate surface of the light reflection plate 413 is thus increased,resulting in an increase in the area of the light reflection portion414. The configuration further prevents the unwanted light from beingreflected off the shafts 441, 442, 443, and 444 to form stray light.

In this embodiment, the light reflection plate 413 has a circular shapein the plan view. The light reflection plate 413 does not necessarilyhave a circular shape and can have an elliptical shape or a rectangularor any other polygonal shape in the plan view.

The thus shaped light reflection plate 413 has a hard layer 415 providedon the lower surface thereof (the other surface, the surface of thelight reflection plate 413 that faces the base 411).

The hard layer 415 is made of a material harder than the material ofwhich the body of the light reflection plate 413 is made, whereby therigidity of the light reflection plate 413 can be increased. The thusincreased rigidity prevents the light reflection plate 413 from beingbent or suppresses the amount of bending when the light reflection plate413 swings. The thickness of the light reflection plate 413 can also bereduced, whereby the moment of inertia of the light reflection plate 413around the first and second axes J1, J2 can be reduced when the lightreflection plate 413 swings therearound.

The material of which the hard layer 415 is made is not limited to aspecific one and can be any material harder than the material of whichthe body of the light reflection plate 413 is made, for example,diamond, quartz, sapphire, lithium tantalate, potassium niobate, or acarbon nitride film. It is, in particular, preferable to use diamond.The hard layer 415 is provided as necessary and can be omitted.

The lower surface of the light reflection plate 413 is fixed to the base411 via the spacer 412. The light reflection plate 413 can thereforeswing around the first axis J1 without the lower surface of the lightreflection plate 413 coming into contact with the shafts 421, 422, theframe 43, or the shafts 441, 442, 443, 444.

Further, the base 411 is located inside the outer circumference of thelight reflection plate 413 in the plan view. Moreover, the area of thebase 411 in the plan view is preferably minimized to the extent that thebase 411 can support the light reflection plate 413 via the spacer 412.In this case, the distance between the shaft 421 and the shaft 422 canbe reduced, while the area of the plate surface of the light reflectionplate 413 is increased.

The frame 43, which has a frame-like shape, is so disposed that itsurrounds the base 411 of the movable portion 41 described above. Inother words, the base 411 of the movable portion 41 is disposed insidethe frame 43, which has a frame-like shape. The frame 43 is supported bythe support member 45 via the shafts 441, 442, 443, and 444. The base411 of the movable portion 41 is supported by the frame 43 via theshafts 421 and 422.

The length of the frame 43 in the direction along the second axis J2 isshorter than the length thereof in the direction along the first axisJ1. That is, a>b is satisfied, where “a” represents the length of theframe 43 in the direction along the first axis J1, and “b” representsthe length of the frame 43 in the direction along the second axis J2.The length of the optical scanner 40 in the direction along the secondaxis J2 can be therefore reduced, while the length necessary for theshafts 421 and 422 is ensured. Since the optical scanner 40 is sodisposed in the enclosure 9 that the second axis J2 is parallel to the Zaxis as will be described later, the thickness of the enclosure (lengthin Z-axis direction) can be reduced when the relationship a>b issatisfied as described above.

Further, the frame 43 has a shape that follows the exterior shape of astructure formed of the base 411 of the movable portion 41 and the pairof shafts 421 and 422 in the plan view. The thus shaped frame 43 can becompact while allowing the first oscillation system formed of themovable portion 41 and the pair of shafts 421 and 422 to oscillate, thatis, the movable portion 41 to oscillate around the first axis J1. Theshape of the frame 43 is not limited to the illustrated shape but can beany frame-like shape.

Each of the shafts 421 and 422 and the shafts 441, 442, 443, and 444 iselastically deformable. The shafts 421 and 422 connect the movableportion 41 to the frame 43 in such a way that the movable portion 41 isswingable around the first axis J1. Further, the shafts 441, 442, 443,and 444 connect the frame 43 to the support member 45 in such a way thatthe frame 43 is swingable around the second axis J2, which isperpendicular to the first axis J1.

The shafts 421 and 422 are disposed on opposite sides of the base 411 ofthe movable portion 41. Further, each of the shafts 421 and 422 has anelongated shape extending in the direction along the first axis J1. Eachof the shafts 421 and 422 has one end connected to the base 411 and theother end connected to the frame 43. Each of the shafts 421 and 422 isfurther so disposed that the central axis thereof coincides with thefirst axis J1. The thus configured shafts 421 and 422 are torsionallydeformed when the movable portion 41 swings around the first axis J1.

The shafts 441, 442 and the shafts 443, 444 are disposed on oppositesides of the frame 43. Each of the shafts 441, 442, 443, and 444 has anelongated shape extending in the direction along the second axis J2.Further, each of the shafts 441, 442, 443, and 444 has one end connectedto the frame 43 and the other end connected to the support member 45.Further, the shafts 441 and 442 are disposed on opposite sides of thesecond axis J2. Similarly, the shafts 443 and 444 are disposed onopposite sides of the second axis J2. The shafts 441, 442, 443, and 444are so configured that the shafts 441 and 442 as a whole and the shafts443 and 444 as a whole are torsionally deformed when the frame 43 swingsaround the second axis J2.

As described above, the movable portion 41 swingable around the firstaxis J1 and the frame 43 swingable around the second axis J2 allow themovable portion 41 (that is, light reflection plate 43) to swing aroundthe two axes perpendicular to each other, the first and second axes J1,J2.

The shapes of the shafts 421 and 422 and the shafts 441, 442, 443, and444 are not limited to those described above, and each of them may, forexample, have a bent or curved portion or a branch in at least oneposition along the shaft.

The base 411, the shafts 421 and 422, the frame 43, the shafts 441, 442,443, and 444, and the support member 45 described above are formedintegrally with each other.

In this embodiment, the base 411, the shafts 421 and 422, the frame 43,the shafts 441, 442, 443, and 444, and the support member 45 are formedby etching an SOI substrate formed of a first Si layer (device layer),an SiO₂ layer (box layer), and a second Si layer (handle layer) stackedin this order. The configuration described above provides the first andsecond oscillation systems with excellent oscillation characteristics.Further, forming the base 411, the shafts 421 and 422, the frame 43, theshafts 441, 442, 443, and 444, and the support member 45 by using theSOI substrate, which allows etching-based micro-processing, not onlyprovides excellent precision in their dimensions but also reduces thesize of the optical scanner 40.

The first Si layer of the SOI substrate forms the base 411, the shafts421 and 422, and the shafts 441, 442, 443, and 444. The shafts 421 and422 and the shafts 441, 442, 443, and 444 therefore have excellentelasticity. Further, the base 411 will not come into contact with theframe 43 when the base 411 pivots around the first axis J1.

Each of the frame 43 and the support member 45 is formed of the SOIsubstrate or the stacked member formed of the first Si layer, the SiO₂layer, and the second Si layer, whereby the frame 43 and the supportmember 45 have excellent rigidity. Further, the SiO₂ layer and thesecond Si layer of the frame 43 not only function as a rib thatincreases the rigidity of the frame 43 but also have a function ofpreventing the movable portion 41 from coming into contact with thepermanent magnet 46.

The upper surface of each of the shafts 421 and 422, the shafts 441,442, 443, and 444, the frame 43, and the support member 45, which arelocated outside the light reflection plate 413 in the plan view,preferably undergoes antireflection processing, which prevents unwantedlight incident on portions other than the light reflection plate 413from forming stray light. The antireflection processing is not limitedto specific one and can, for example, be formation of an antireflectionfilm (dielectric multilayer film), surface roughing, and surfaceblackening.

The materials of which the base 411, the shafts 421 and 422, and theshafts 441, 442, 443, and 444 are made and the method for forming thesecomponents described above are presented by way of example and are notnecessarily used in the invention.

Further, in this embodiment, the spacer 412 and the light reflectionplate 413 are also formed by etching the SOI substrate. The spacer 412is formed of a stacked member of the SiO₂ layer and the second Si layerof the SOI substrate. The light reflection plate 413 is formed of thefirst Si layer of the SOI substrate. The spacer 412 and the lightreflection plate 413 bonded to each other can thus be manufactured in asimple, highly precise manner by forming the spacer 412 and the lightreflection plate 413 based on the SOI substrate as described above.

The spacer 412 is bonded to the base 411 with an adhesive, a waxmaterial, or any other suitable bonding material (not shown).

The permanent magnet 46 is bonded to the lower surface of the frame 43described above. A method for bonding the permanent magnet 46 to theframe 43 is not limited to a specific one and can, for example, be abonding method using an adhesive. The permanent magnet 46 is magnetizedin a direction inclined to the first and second axes J1, J2 in the planview.

In this embodiment, the permanent magnet 46 has an elongated shape(rod-like shape) extending in a direction inclined to the first andsecond axes J1, J2. The permanent magnet 46 is magnetized in theelongated direction. That is, the permanent magnet 46 is so magnetizedthat one end thereof forms an S pole and the other end thereof forms anN pole . Further, the permanent magnet 46 is so disposed that it issymmetrical with respect to the intersection of the first axis J1 andthe second axis J2 in the plan view.

The inclination angle θ of the direction in which the permanent magnet46 is magnetized (direction in which permanent magnet 46 extends) withrespect to the second axis J2 is not limited to a specific value but ispreferably greater than or equal to 30° but smaller than or equal to60°, more preferably greater than or equal to 45° but smaller than orequal to 60°, still more preferably 45°. The thus disposed permanentmagnet 46 allows the movable portion 41 to swing around the second axisJ2 in a smooth, reliable manner.

The permanent magnet 46 can preferably be, for example, a neodymiummagnet, a ferrite magnet, a samarium cobalt magnet, an Alnico magnet, ora bonded magnet. The permanent magnet 46 is a magnetized hard magneticmaterial and formed, for example, by placing a hard magnetic materialnot yet having been magnetized on the frame 43 and magnetizing theentire structure. The reason for this is that an attempt to place thepermanent magnet 46, which has been magnetized, on the frame 43 may notresult in successful placement of the permanent magnet 46 in a desiredposition in some cases because magnetic fields produced by objectsoutside the apparatus and other parts in the apparatus affect theplacement of the permanent magnet 46.

The coil 47 is disposed immediately below the permanent magnet 46,whereby a magnetic field produced by the coil 47 can act on thepermanent magnet 46 in an efficient manner. As a result, the electricityconsumption and the size of the optical scanner 40 can be reduced. Thecoil 47 is wound around the magnetic core 48. The magnetic fieldproduced by the coil 47 can thus act on the permanent magnet 46 in anefficient manner. The magnetic core 48 may be omitted.

The thus configured coil 47 is electrically connected to the voltageapplying section 49. When the voltage applying section 49 applies avoltage to the coil 47, the coil 47 produces a magnetic field having amagnetic flux perpendicular to the first and second axes J1, J2.

The voltage applying section 49 includes a first voltage generator 491that generates a first voltage V1 for causing the movable portion 41 topivot around the first axis J1, a second voltage generator 492 thatgenerates a second voltage V2 for causing the movable portion 41 topivot around the second axis J2, and a voltage superimposing section 493that superimposes the first voltage V1 and the second voltage V2 on eachother, and the superimposed voltage from the voltage superimposingsection 493 is applied to the coil 47, as shown in FIG. 6.

The first voltage V1 (voltage for primary scan), which is generated bythe first voltage generator 491, periodically changes at a period T1, asshown in FIG. 7A. The first voltage V1 has a sinusoidal waveform. Thefrequency of the first voltage V1 (1/T1) preferably ranges, for example,from 10 to 40 kHz. In this embodiment, the frequency of the firstvoltage V1 is set to be equal to a torsional resonant frequency (f1) ofthe first oscillation system formed of the movable portion 41 and thepair of shafts 421 and 422, whereby the angle of pivotal motion of themovable portion 41 around the first axis J1 can be increased.

On the other hand, the second voltage V2 (voltage for secondary scan),which is generated by the second voltage generator 492, periodicallychanges at a period T2 different from the period T1, as shown in FIG.7B. The second voltage V2 has a saw-toothed waveform. The frequency ofthe second voltage V2 (1/T2) only needs to differ from the frequency ofthe first voltage V1 (1/T1) and preferably ranges, for example, from 30to 80 Hz (about 60 Hz). In this embodiment, the frequency of the secondvoltage V2 is adjusted to be a frequency different from a torsionalresonant frequency (resonant frequency) of the second oscillation systemformed of the movable portion 41, the pair of shafts 421 and 422, theframe 43, the two pairs of shafts 441, 442, 443, and 444, and thepermanent magnet 46.

The thus set frequency of the second voltage V2 is preferably lower thanthe frequency of the first voltage V1. In this case, the movable portion41 is allowed to swing not only around the first axis J1 at thefrequency of the first voltage V1 but also around the second axis J2 atthe frequency of the second voltage V2 in a more reliable, smoothermanner.

Now, let f1 [Hz] be the torsional resonant frequency of the firstoscillation system and f2 [Hz] be the torsional resonant frequency ofthe second oscillation system, and f1 and f2 preferably satisfy f2<f1,more preferably 10×f2≦f1. Satisfying the relationship described aboveallows the movable portion 41 to pivot not only around the first axis J1at the frequency of the first voltage V1 but also around the second axisJ2 at the frequency of the second voltage V2 in a smoother manner. Onthe other hand, when f1≦f2, the first oscillation system can oscillateat the frequency of the second voltage V2.

The thus configured first voltage generator 491 and second voltagegenerator 492 are connected to the controller 6 and driven based onsignals from the controller 6. The voltage superimposing section 493 isconnected to the first voltage generator 491 and the second voltagegenerator 492.

The voltage superimposing section 493 includes an adder 493 a forapplying a voltage to the coil 47. The adder 493 a receives the firstvoltage V1 from the first voltage generator 491, receives the secondvoltage V2 from the second voltage generator 492, superimposes thevoltages on each other, and applies the resultant voltage to the coil47.

A description will next be made of a method for driving the opticalscanner 40. It is assumed that the frequency of the first voltage V1 isset to be equal to the torsional resonant frequency of the firstoscillation system, and that the frequency of the second voltage V2 isset to be not only different from the torsional resonant frequency ofthe second oscillation system but also smaller than the frequency of thefirst voltage V1 (for example, the frequency of the first voltage V1 isset at 15 kHz, and the frequency of the second voltage V2 is set at 60Hz).

For example, when the voltage superimposing section 493 superimposes thefirst voltage V1 shown in FIG. 7A and the second voltage V2 shown inFIG. 7B on each other and applies the superimposed voltage to the coil47, the first voltage V1 produces the following alternately switchingmagnetic fields: a magnetic field that causes the one end (N pole) ofthe permanent magnet 46 to be attracted to the coil 47 and the other end(S pole) of the permanent magnet 46 to be repulsed from the coil 47 (themagnetic field is referred to as “magnetic field A1”); and a magneticfield that causes the one end (N pole) of the permanent magnet 46 to berepulsed from the coil 47 and the other end (S pole) of the permanentmagnet 46 to be attracted to the coil 47 (the magnetic field is referredto as “magnetic field A2”).

When the magnetic field A1 and the magnetic field A2 are alternatelyswitched from each other as described above, oscillation having atorsional oscillation component around the first axis J1 is excited inthe frame 43, and the oscillation causes the shafts 421 and 422 to betorsionally deformed and hence the movable portion 41 to swing aroundthe first axis J1 at the frequency of the first voltage V1. Since thefrequency of the first voltage V1 is equal to the torsional resonantfrequency of the first oscillation system, the resonance action(resonant oscillation) allows the movable portion 41 to swing at a largeamplitude. That is, even when the oscillation produced in the frame 43and having a torsional oscillation component around the first axis J1has a small amplitude, the angle of swing motion of the movable portion41 around the first axis J1 produced by the oscillation can beincreased.

On the other hand, the second voltage V2 produces the followingalternately switching magnetic fields: a magnetic field that causes theone end (N pole) of the permanent magnet 46 to be attracted to the coil47 and the other end (S pole) of the permanent magnet 46 to be repulsedfrom the coil 47 (the magnetic field is referred to as “magnetic fieldB1”); and a magnetic field that causes the one end (N pole) of thepermanent magnet 46 to be repulsed from the coil 47 and the other end (Spole) of the permanent magnet 46 to be attracted to the coil 47 (themagnetic field is referred to as “magnetic field B2”).

When the magnetic field B1 and the magnetic field B2 are alternatelyswitched from each other as described above, the shafts 441, 442 and theshafts 443, 444 are torsionally deformed and the frame 43 along with themovable portion 41 swings around the second axis J2 at the frequency ofthe second voltage V2. Since the frequency of the second voltage V2 isset to be greatly lower than the frequency of the first voltage V1 andthe torsional resonant frequency of the second oscillation system is setto be lower than the torsional resonant frequency of the firstoscillation system as described above, the pivotal motion of the movableportion 41 around the first axis J1 will not occur at the frequency ofthe second voltage V2.

As described above, when the first voltage V1 and the second voltage V2superimposed on each other are applied to the coil 47 in the opticalscanner 40, the movable portion 41 can pivot not only around the firstaxis J1 at the frequency of the first voltage V1 but also around thesecond axis J2 at the frequency of the second voltage V2. The thusconfigured optical scanner 40 allows the cost and size of the apparatusto be reduced and causes the movable portion 41 to swing around thefirst and second axes J1, J2 based on the electro-magnetic drive method(moving magnet method), whereby the drawing laser light LL reflected offthe light reflection portion 414 can be deflected for two-dimensionalscanning. Further, since the number of parts that form the drive source(permanent magnet and coil) can be reduced, the resultant configurationcan be simple and compact. Moreover, since the coil 47 is set apart fromthe oscillation systems of the optical scanner 40, heat generated by thecoil 47 will not adversely affect the oscillation systems.

The configuration of the optical scanner 40 has been described above indetail. According to the gimbal-type, two-dimensional-scanning opticalscanner 40 described above, which is alone capable of deflecting thedrawing laser light LL for two-dimensional scanning, the size of theoptical scan section 4 can be reduced and alignment adjustment thereofcan be readily made as compared, for example, with a configuration inwhich two one-dimensional-scanning optical scanners are combined witheach other to deflect the drawing laser light LL for two-dimensionalscanning.

The optical scanner 40 is an electro-magnetically driven optical scannerdriven by using the permanent magnet 46 and the coil 47. The thusconfigured optical scanner 40 requires the permanent magnet 46 and thecoil 47 to face each other as shown in FIG. 5, which increases thethickness of the optical scanner 40 (length in the direction of an axisJ3 that intersects the intersection of the first and second axes J1, J2and is perpendicular to the two axes). However, the size of the opticalscanner 40 in the in-plane direction in the plane including the firstand second axes J1, J2 can be reduced. As described above, the opticalscanner 40, the size of which in the in-plane direction described aboveis reduced instead of the size in the thickness direction, can form anoptical scanner suitable for the image display apparatus 1.

The optical scanner 40 having the configuration described above is sodisposed in the enclosure 9 that the light reflection portion 414 isperpendicular to the XY plane when the optical scanner 40 is not driven(when no voltage is applied to the coil 47) as shown in FIGS. 1 and 3.In other words, the optical scanner 40 is so disposed in the enclosure 9that the plane including the first and second axes J1, J2 isperpendicular to the XY plane (the axis J3 is present in the plane F).Since the optical scanner 40 has a small size in the in-plane directionin the plane including the first and second axes J1, J2 as describedabove, disposing the optical scanner 40 as described above allows thesize (thickness) of the image display apparatus 1 (enclosure 9) to bereduced. Although the optical scanner 40 is not so thin in the directionof the axis J3 but is so disposed in the image display apparatus 1 thatthe axis J3 is present in the plane F, an increase in the size of theapparatus resulting from the thickness in the direction of the axis J3is minimized.

Further, the drawing laser light LL having passed through the prism 3 isincident on the light reflection portion 414 in a direction inclined tothe axis J3. When the drawing laser light LL is incident on the lightreflection portion 414 in a direction inclined to the axis J3 (normal tolight reflection surface 414 a), the drawing laser light LL deflected bythe optical scanner 40 for scanning can exit out of the enclosure 9without interfering with other members (prism 3, for example) in theenclosure 9. It is therefore not necessary to provide a flat mirror, aprism, or any other optical component for changing the optical path ofthe drawing laser light LL deflected by the optical scanner 40 forscanning, whereby the size of the image display apparatus 1 can bereduced.

Further, in the optical scanner 40, the amplitude of the oscillation(angle of swing motion) of the resonantly driven movable portion 41around the first axis J1 is greater than the amplitude of theoscillation (angle of swing motion) of the non-resonantly driven movableportion 41 around the second axis J2. The thus configured opticalscanner 40 is so disposed that the amplitude in the Z-axis direction isgreater than the amplitude in the in-plane direction in the XY plane.That is, the optical scanner 40 is so disposed that the first axis J1 isparallel to the in-plane direction in the XY plane (coincides with thefirst plane F) and the second axis J2 is parallel to the Z axis.Disposing the optical scanner 40 as described above provides thefollowing advantageous effects.

Since the drawing laser light LL is incident on the light reflectionportion 414 in a direction inclined to the axis J3 as described above,the drawable region S irradiated with the drawing laser light LLdeflected by the light reflection portion 414 for two-dimensionalscanning is shaped as shown in FIGS. 8A and 8B. FIG. 8A shows a drawableregion produced when the optical scanner 40 is so disposed that thefirst axis J1 is parallel to the in-plane direction in the XY plane andthe second axis J2 is parallel to the Z axis as described in thisembodiment of the invention, and FIG. 8B shows a drawable regionproduced when the optical scanner 40 is so disposed that the first axisJ1 is parallel to the Z axis and the second axis J2 is parallel to thein-plane direction in the XY plane as in the related art.

As shown in FIGS. 8A and 8B, the distortion of the drawable region S inFIG. 8A, which shows this embodiment of the invention, is smaller thanin FIG. 8B, which shows related art, whereby this embodiment of theinvention provides a larger effective rectangular drawing region (regionactually irradiated with the drawing laser light LL for image display)S′ ensured in the drawable region S. Therefore, the drawable region Scan be used more effectively in FIG. 8A than in FIG. 8B, and a moreefficient, larger image can be drawn.

Since the length “b” of the frame 43 along the second axis J2 is shorterthan the length “a” of the frame 43 along the first axis J1 as describedabove, disposing the optical scanner 40 in the enclosure 9 as describedabove reduces the length of the optical scanner 40 in the Z-axisdirection, whereby the thickness of the image display apparatus 1 can bereduced.

1-4. Detector

The detector 5 has a function of detecting the intensity of the drawinglaser light LL (each of the laser light fluxes RR, GG, and BB). The thusconfigured detector 5 includes a light receiving device 51, such as aphotodiode, disposed in the enclosure 9. The light incident surface 31of the prism 3 is configured to slightly (at a reflectance of about0.1%, for example) reflect the laser light fluxes RR, GG, and BB, andthe light receiving device 51 is located on the optical paths of thereflected light fluxes. The light receiving device 51 outputs a signal(voltage) having a magnitude according to the intensity of each of thereceived reflected light fluxes, and the intensity of each of the laserlight fluxes RR, GG, and BB can be detected based on the signal.

Information on the detected intensities of the laser light fluxes RR,GG, and BB is sent to the controller 6, which then controls the driveoperation of the laser light sources 21R, 21G, and 21B based on thereceived information.

Specifically, the reflectance and transmittance representing how muchthe collimator lenses 22R, 22G, and 22B and the dichroic mirrors 23R,23G, and 23B reflect and transmit the laser light fluxes RR, GG, and BBand the reflectance representing how much the light incident surface 31reflects the laser light fluxes RR, GG, and BB are measured in advance,and the measurement information is stored in a memory (not shown) in thecontroller 6.

Subsequently, for example, before image drawing is initiated, thecontroller 6 sends a drive signal of a predetermined magnitude (voltage)to the drive circuit associated with the laser light source 21R, whichthen emits the laser light flux RR. Part of the laser light flux RR isthen reflected off the light incident surface 31 of the prism 3, and thelight receiving device 51 receives the reflected light and detects theintensity thereof. The actual intensity of the laser light flux RRemitted from laser light source 21R is then determined based on thereflectance stored in the memory described above and representing howmuch each of the portions described above reflects the laser light fluxRR. The relationship between the intensity of the laser light flux RRand the magnitude (voltage value) of the drive signal is thusdetermined, and the magnitude of the drive signal necessary to providethe laser light flux RR of a predetermined intensity is found.

The relationship is stored in the memory described above. To draw animage, the controller 6 sends the drive circuit a desired drive signalthat causes the laser light source 21R to emit a laser light flux RR ofa desired intensity based on the relationship. The same holds true forthe laser light fluxes GG and BB. Specifically, the relationship betweenthe intensity of each of the laser light fluxes GG and BB and themagnitude of the corresponding drive signal is determined, and thecontroller 6 sends the drive circuit desired drive signals that causethe laser light sources 21G and 21B to emit laser light fluxes GG and BBof desired intensities based on the determined relationships.

Drawing laser light LL of a desired color and luminance can thus beproduced, and the image display characteristics are improved.

The above description has been made with reference to the case where therelationship between the intensity of the laser light flux RR and themagnitude (voltage value) of the drive signal is provided before imagedrawing is initiated. The relationship is not necessarily providedbefore image drawing is initiated and may, for example, be provided inthe course of image drawing. The effective drawing region S′ in thedrawable region S is irradiated with the drawing laser light LL, whereasthe other region (non-drawing region S″) is not irradiated therewith, asdescribed above. In view of the fact described above, the relationshipbetween the intensity of the laser light flux RR and the magnitude(voltage value) of the drive signal may alternatively be provided asdescribed above during a period when an image is being drawn but themovable portion 41 (light reflection portion 414) faces the non-drawingregion S″ and no drawing laser light LL is outputted.

1-5. Controller

The controller 6 has a function of controlling the operation of thedrawing light source unit 2 and the light scan section 4. Specifically,the controller 6 drives the optical scanner 40 to cause the movableportion 41 to swing around the first and second axes J1, J2 and drivesthe drawing light source unit 2 to emit the drawing laser light LL insynchronization with the swing motion of the movable portion 41. Thecontroller 6 drives the laser light sources 21R, 21G, and 21B to emitlaser light fluxes RR, GG, and BB of predetermined intensities atpredetermined timings based, for example, on image data sent from anexternal computer so that the drawing laser light LL of a predeterminedcolor and intensity (luminance) is emitted at a predetermined timing. Asa result, an image according to the image data is displayed on theobject 10.

The configuration of the image display apparatus 1 has been described indetail.

In the image display apparatus 1 described above, the members thereof,that is, the laser light sources 21R, 21G, and 21B, the collimatorlenses 22R, 22G, and 22B, the dichroic mirrors 23R, 23G, and 23B, theprism 3, the optical scanner 40, and the light receiving device 51 arearranged in a flat plane (the same plane) extending in the direction inwhich the XY plane extends. The optical axes of the laser light fluxesRR, GG, and BB emitted from the laser light sources 21R, 21G, and 21Band the optical axis of the drawing laser light LL, which is thecombination of the laser light fluxes RR, GG, and BB, are present in thesame plane (first plane F) parallel to the XY plane until the drawinglaser light LL is incident on the optical scanner 40.

Further, in the image display apparatus 1, since the prism 3 inclinesthe optical axis of the drawing laser light LL within the first plane F,the components of the image display apparatus 1 (optical scanner 40, inparticular) can be arranged in the flat plane. In this case, thecomponents of the image display apparatus 1 can be aligned with eachother in the flat plane, whereby the image display apparatus 1 can bereadily assembled. Further, in the image display apparatus 1, since theprism 3 shapes the drawing laser light LL, excellent image displaycharacteristics are provided.

2. Head-up Display

A description will next be made of the configuration of a head-updisplay based on the image display apparatus according to the embodimentof the invention.

FIG. 9 is a perspective view showing a head-up display based on theimage display apparatus according to the embodiment of the invention.

In a head-up display system 200, the image display apparatus 1 isaccommodated in a dashboard of an automobile to form a head-up display210, as shown in FIG. 9. The head-up display 210 can display apredetermined image, such as a displayed image that guides a driver to adestination, on a windshield 220. The head-up display system 200 is notnecessarily used with an automobile but may be used, for example, withan airplane and a ship.

3. Head-mounted Display

A description will next be made of a head-mounted display based on theimage display apparatus according to the embodiment of the invention(head-mounted display according to an embodiment of the invention).

FIG. 10 is a perspective view showing a head-mounted display accordingto an embodiment of the invention.

A head-mounted display 300 includes glasses 310 and the image displayapparatus 1 mounted on the glasses 310, as shown in FIG. 10. The imagedisplay apparatus 1 displays a predetermined image in a display section(light reflector) 320 provided in a portion of the glasses 310 thatoriginally functions as a lens, and the image is viewed with one of theeyes.

The display section 320 may be transparent or opaque. When the displaysection 320 is transparent, information from the image display apparatus1 can be superimposed on information from the real world and thesuperimposed information can be viewed. Further, the display section 320only needs to reflect at least part of light incident thereon and can,for example, be a half-silvered mirror.

The head-mounted display 300 may alternatively be provided with twoimage display apparatus 1, and two display sections display imagesviewed with both eyes.

The image display apparatus and the head-mounted display according tothe embodiments of the invention have been described with reference tothe drawings, but the invention is not limited thereto. Theconfiguration of each of the components can be replaced with anarbitrary configuration having the same function. Further, otherarbitrary components may be added to the embodiments of the invention.

What is claimed is:
 1. An image display apparatus comprising: aplurality of light source sections each of which emits a light flux; alight combining section that combines the light fluxes emitted from theplurality of light source sections; an optical scan section that swingsaround a first axis and a second axis intersected with the first axis todeflect a combined light from the light combining section fortwo-dimensional scanning; and a controller that controls an amplitude ofa swing motion of the optical scan section around the first axis to begreater than the amplitude of the swing motion of the optical scansection around the second axis, wherein an optical axis of each of thelight fluxes emitted from the plurality of light source sections anddirected through the light combining section toward the optical scansection and the first axis are present in a first plane, the opticalscan section has a light reflection surface configured to intersect withthe first plane, and the light reflection surface is irradiated with thecombined light emitted from the light combining section and traveling ina direction inclined to a normal to the light reflection surface.
 2. Theimage display apparatus according to claim 1, wherein the optical scansection includes a movable portion having the light reflection surface,a frame that surrounds the movable portion, a support member thatsupports the frame, a first shaft that connects the movable portion tothe frame in such away that the movable portion is swingable around thefirst axis relative to the frame, and a second shaft that connects theframe to the support member in such a way that the frame is swingablearound the second axis relative to the support member.
 3. The imagedisplay apparatus according to claim 2, wherein a width of the frame ina direction perpendicular to the first plane is smaller than the widthof the frame in an in-plane direction in the first plane.
 4. The imagedisplay apparatus according to claim 2, wherein the optical scan sectionfurther includes a permanent magnet provided on the frame and a coilthat faces the frame and produces a magnetic field that acts on thepermanent magnet.
 5. The image display apparatus according to claim 1,wherein the light reflection surface resonantly swings around the firstaxis.
 6. The image display apparatus according to claim 1, furthercomprising a prism that is provided on an optical path between the lightcombining section and the optical scan section, inclines an optical axisof the combined light from the light combining section, and changes across-sectional shape of the combined light.
 7. The image displayapparatus according to claim 6, wherein the light flux emitted from eachof the light source sections is linearly polarized light that behaves ass-polarized light with respect to a light incident surface of the prism.8. The image display apparatus according to claim 6, wherein the prismchanges the cross-sectional shape of the combined light from the lightcombining section by increasing a width of the combined light from thelight combining section in an in-plane direction in the first plane. 9.The image display apparatus according to claim 6, wherein a lightexiting surface of the prism is a light collecting lens surface.
 10. Theimage display apparatus according to claim 6, further comprising adetector that detects an amount of light emitted from each of the lightsource sections and reflected off a light incident surface of the prism,wherein drive operation of the light source section is controlled basedon the amount of light detected by the detector.
 11. The image displayapparatus according to claim 1, wherein an angle of radiation of thelight flux emitted from each of the plurality of light source sectionsand directed in a direction perpendicular to the first plane is set tobe greater than the angle of radiation of the light flux emitted in anin-plane direction in the first plane.
 12. The image display apparatusaccording to claim 1, wherein the plurality of light source sections,the light combining section, and the optical scan section are arrangedin an in-plane direction in the first plane.
 13. An image displayapparatus comprising: a plurality of light source sections each of whichemits a light flux; a light combining section that combines the lightfluxes emitted from the plurality of light source sections; and anoptical scan section that swings around a first axis and a second axisintersected with the first axis to deflect a combined light from thelight combining section for two-dimensional scanning, wherein an opticalaxis of each of the light fluxes emitted from the plurality of lightsource sections and directed through the light combining section towardthe optical scan section and the first axis are present in a firstplane, the optical scan section has a light reflection surfaceconfigured to intersect with the first plane, the light reflectionsurface is irradiated with the combined light emitted from the lightcombining section and traveling in a direction inclined to a normal tothe light reflection surface, and an amplitude of a swing motion of theoptical scan section around the first axis is greater than the amplitudeof the swing motion of the optical scan section around the second axis.14. A head-mounted display comprising: a light reflector that reflectsat least part of light incident thereon; and an image display apparatusthat irradiates light to the light reflector, the image displayapparatus including a plurality of light source sections each of whichemits a light flux, a light combining section that combines the lightfluxes emitted from the plurality of light source sections, an opticalscan section that swings around a first axis and a second axisintersected with the first axis to deflect a combined light from thelight combining section for two-dimensional scanning, and a controllerthat controls an amplitude of a swing motion of the optical scan sectionaround the first axis to be greater than the amplitude of the swingmotion of the optical scan section around the second axis, wherein anoptical axis of each of the light fluxes emitted from the plurality oflight source sections and directed through the light combining sectiontoward the optical scan section and the first axis are present in afirst plane, the optical scan section has a light reflection surfaceconfigured to intersect with the first plane, and the light reflectionsurface is irradiated with the combined light emitted from the lightcombining section and traveling in a direction inclined to a normal tothe light reflection surface.
 15. The head-mounted display according toclaim 14, wherein the optical scan section includes a movable portionhaving the light reflection surface, a frame that surrounds the movableportion, a support member that supports the frame, a first shaft thatconnects the movable portion to the frame in such away that the movableportion is swingable around the first axis relative to the frame, and asecond shaft that connects the frame to the support member in such a waythat the frame is swingable around the second axis relative to thesupport member.
 16. The head-mounted display according to claim 15,wherein a width of the frame in a direction perpendicular to the firstplane is smaller than the width of the frame in an in-plane direction inthe first plane.
 17. The head-mounted display according to claim 15,wherein the optical scan section further includes a permanent magnetprovided on the frame and a coil that faces the frame and produces amagnetic field that acts on the permanent magnet.
 18. The head-mounteddisplay according to claim 14, wherein the light reflection surfaceresonantly swings around the first axis.
 19. The head-mounted displayaccording to claim 14, further comprising a prism that is provided on anoptical path between the light combining section and the optical scansection, inclines an optical axis of the combined light from the lightcombining section, and changes a cross-sectional shape of the combinedlight.
 20. The head-mounted display according to claim 19, wherein thelight flux emitted from each of the light source sections is linearlypolarized light that behaves as s-polarized light with respect to alight incident surface of the prism.